| Degenerative disc disease (DDD) is the most common diseases in spinalsurgery field, it is the main reason for the backache of the adult, which havecaused enormous economic loss and social burden. Spinal fusion surgery hasbeen widely used to treat degenerative disc disease. Spinal fusion achievesinterbody fusion through the fixed unstable vertebral in order to relieve lumbarpain, its advantages include the remodeling of physiological lordosis, andproviding the inherent stability. However, the clinical improvement rate failedto reach a satisfactory extent. The serious complications include: infection,accounting for2-6%; implant failure, accounting for5-31%; pseudoarthrosis,accounting for4-5%, moreover, the most important and noteworthycomplication is fusion region of symptomatic or asymptomatic adjacentsegment degeneration (adjacent the segment degeneration, ASD), accountingfor5-100%. Therefore, posterior lumbar non-fusion devices have beendeveloped to preserve vertebral column movement, change load pattern ofinstability segment utmostly to alleviate the LBP（low back pain）and restrictabnormal action, maintain the stability of the spine, as well as prevent ormitigate the ASD（Adjacent segment degeneration).Interspinous dynamic stabilization is one way in the non-fusion spinesurgery. The interspinous process（ISP） which is implanted in the upper andlower interspinous, helps to alleviate spinal compression and increase size ofintervertebral foramen, so the symptoms of spinal canal stenosis anddecompression of nerve roots can be relieved accordingly. Preserving spinousprocess and superspinous ligament can keep the stability of posterior columnand alleviate pains in low back and legs. Interspinous dynamic stabilization surgery is easy to carry out due to simple operation and minimal trauma. Butthe long-term effect of IPD is uncertain since the period of application is shortand overall basic research of all kinds of IPDs is absent.This project involves the field of spinal surgery, it is medical devicetechnology. The Viking system has the obvious design features.Its core is anelastic spring which can be deformed, therefore allowing to distributestiffnesses along the spine. Thanks to its anatomical shape, consisting of twosaddle-shaped ends, the device can be implanted between the spinous processesof two adjoining vertebras, it is fixed with a Dacron ligament passing throughthe holes in the saddles and blocked with a titanium clip.The device is made in PAEK a kind of biocompatible polymer. Thismaterial, in addition to being lighter, has also got optimal mechanical features,in particular its stiffness is very similar to that of human cortical bone.This study is to choose Viking system to assess the biomechanical andclinical applications. In this study，mainly includes three aspects:Firstly, the biomechanical testing of Viking system;Secondly, the surgical procedures of Viking system;Thirdly, the clinical application of Viking system.Methods:1、Designing and building a Viking model, detect Viking mechanicscharacteristics through static mechanical tests and dynamic fatigue test, andanalyze the Viking system pressure-displacement curve and the dynamic cycle-displacement curve. In static pressure experiments, equipment is given verticalpressure, with observing displacement degree. The dynamic fatigue test is tosimulate spine flexion, extension, lateral bending and rotational motion, torecord the extent of the displacement.2、Analyzing the stress distribution and biomechanic of Viking by thefinite element method. 3、Detailed introducing Viking surgical operating techniques,because itis easier to install than other similar productsand，so viking is easier to acceptedby clinician.4、Exploring the effects of cases of early clinical applications of Vikingsystem.Results:1、Viking is a dynamic interspinous lumbar system. It allows deformations.Under static compressure, the equipments can withstand the pressure of morethan3500[N] and does not occur destruction. Under fatigue，instruments canwithstand5million cycles without damage. Elastic strength is30000N/m2;maximum compression distance reach to2.5mm; the maximum forward andbackward bending angle is20°; and the maximum side bending angle is20°.2、Stress peak of Viking are in the middle of the main part and the partwhere the upper and lower saddle contact with spinous process bone surface.The maximum stress reach to379Mpa. The rest of the stress are more uniformwith the average stress94.6Mpa.It is able to transfer load along the spine and preserve the kinematicmovements of segment, working at the same time as a"shock absorber". Vikingcan effectively prevent or mitigate the ASD（Adjacent segment degeneration).3、Viking’s surgical implants is fast and simple. The device is made inPAEK a biocompatible polymer.This material,in addition to being lighter, hasalso got optimal mechanical features, in particular its stiffness is very similar tothat of human cortical bone. The shape of Viking is suitable for human anatomywithout sharp edges, therefore, it has more security and biologicalcharacteristics.4、Currently，the application of Viking system is in infancy, and itslong-term efficacy and possible complications after implantation need further study. The clinical application of the Viking system is in infancy, and itslong-term efficacy and possible complications after implantation and otherissues still need further study. This article discusses the clinical case for earlycases, the long-term efficacy need to further clinical follow-up and observetogether with international friends. |
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